<?php
/**
 * CDbSchema class file.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.yiiframework.com/
 * @copyright Copyright &copy; 2008-2011 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

/**
 * CDbSchema is the base class for retrieving metadata information.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @version $Id: CDbSchema.php 3069 2011-03-14 00:28:38Z qiang.xue $
 * @package system.db.schema
 * @since 1.0
 */
abstract class CDbSchema extends CComponent
{
    /**
     * @var array the abstract column types mapped to physical column types.
     * @since 1.1.6
     */
    public $columnTypes = array ();
    
    private $_tableNames = array ();
    private $_tables = array ();
    private $_connection;
    private $_builder;
    private $_cacheExclude = array ();
    
    /**
     * Loads the metadata for the specified table.
     * @param string $name table name
     * @return CDbTableSchema driver dependent table metadata, null if the table does not exist.
     */
    abstract protected function loadTable($name);
    
    /**
     * Constructor.
     * @param CDbConnection $conn database connection.
     */
    public function __construct($conn)
    {
        $this->_connection = $conn;
        foreach ( $conn->schemaCachingExclude as $name )
            $this->_cacheExclude [$name] = true;
    }
    
    /**
     * @return CDbConnection database connection. The connection is active.
     */
    public function getDbConnection()
    {
        return $this->_connection;
    }
    
    /**
     * Obtains the metadata for the named table.
     * @param string $name table name
     * @return CDbTableSchema table metadata. Null if the named table does not exist.
     */
    public function getTable($name)
    {
        if (isset ( $this->_tables [$name] ))
            return $this->_tables [$name];
        else {
            if ($this->_connection->tablePrefix !== null && strpos ( $name, '{{' ) !== false)
                $realName = preg_replace ( '/\{\{(.*?)\}\}/', $this->_connection->tablePrefix . '$1', $name );
            else
                $realName = $name;
            
     // temporarily disable query caching
            if ($this->_connection->queryCachingDuration > 0) {
                $qcDuration = $this->_connection->queryCachingDuration;
                $this->_connection->queryCachingDuration = 0;
            }
            
            if (! isset ( $this->_cacheExclude [$name] ) && ($duration = $this->_connection->schemaCachingDuration) > 0 && $this->_connection->schemaCacheID !== false && ($cache = Yii::app ()->getComponent ( $this->_connection->schemaCacheID )) !== null) {
                $key = 'yii:dbschema' . $this->_connection->connectionString . ':' . $this->_connection->username . ':' . $name;
                if (($table = $cache->get ( $key )) === false) {
                    $table = $this->loadTable ( $realName );
                    if ($table !== null)
                        $cache->set ( $key, $table, $duration );
                }
                $this->_tables [$name] = $table;
            } else
                $this->_tables [$name] = $table = $this->loadTable ( $realName );
            
            if (isset ( $qcDuration )) // re-enable query caching
                $this->_connection->queryCachingDuration = $qcDuration;
            
            return $table;
        }
    }
    
    /**
     * Returns the metadata for all tables in the database.
     * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
     * @return array the metadata for all tables in the database.
     * Each array element is an instance of {@link CDbTableSchema} (or its child class).
     * The array keys are table names.
     * @since 1.0.2
     */
    public function getTables($schema = '')
    {
        $tables = array ();
        foreach ( $this->getTableNames ( $schema ) as $name ) {
            if (($table = $this->getTable ( $name )) !== null)
                $tables [$name] = $table;
        }
        return $tables;
    }
    
    /**
     * Returns all table names in the database.
     * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
     * If not empty, the returned table names will be prefixed with the schema name.
     * @return array all table names in the database.
     * @since 1.0.2
     */
    public function getTableNames($schema = '')
    {
        if (! isset ( $this->_tableNames [$schema] ))
            $this->_tableNames [$schema] = $this->findTableNames ( $schema );
        return $this->_tableNames [$schema];
    }
    
    /**
     * @return CDbCommandBuilder the SQL command builder for this connection.
     */
    public function getCommandBuilder()
    {
        if ($this->_builder !== null)
            return $this->_builder;
        else
            return $this->_builder = $this->createCommandBuilder ();
    }
    
    /**
     * Refreshes the schema.
     * This method resets the loaded table metadata and command builder
     * so that they can be recreated to reflect the change of schema.
     */
    public function refresh()
    {
        if (($duration = $this->_connection->schemaCachingDuration) > 0 && $this->_connection->schemaCacheID !== false && ($cache = Yii::app ()->getComponent ( $this->_connection->schemaCacheID )) !== null) {
            foreach ( array_keys ( $this->_tables ) as $name ) {
                if (! isset ( $this->_cacheExclude [$name] )) {
                    $key = 'yii:dbschema' . $this->_connection->connectionString . ':' . $this->_connection->username . ':' . $name;
                    $cache->delete ( $key );
                }
            }
        }
        $this->_tables = array ();
        $this->_tableNames = array ();
        $this->_builder = null;
    }
    
    /**
     * Quotes a table name for use in a query.
     * If the table name contains schema prefix, the prefix will also be properly quoted.
     * @param string $name table name
     * @return string the properly quoted table name
     * @see quoteSimpleTableName
     */
    public function quoteTableName($name)
    {
        if (strpos ( $name, '.' ) === false)
            return $this->quoteSimpleTableName ( $name );
        $parts = explode ( '.', $name );
        foreach ( $parts as $i => $part )
            $parts [$i] = $this->quoteSimpleTableName ( $part );
        return implode ( '.', $parts );
    
    }
    
    /**
     * Quotes a simple table name for use in a query.
     * A simple table name does not schema prefix.
     * @param string $name table name
     * @return string the properly quoted table name
     * @since 1.1.6
     */
    public function quoteSimpleTableName($name)
    {
        return "'" . $name . "'";
    }
    
    /**
     * Quotes a column name for use in a query.
     * If the column name contains prefix, the prefix will also be properly quoted.
     * @param string $name column name
     * @return string the properly quoted column name
     * @see quoteSimpleColumnName
     */
    public function quoteColumnName($name)
    {
        if (($pos = strrpos ( $name, '.' )) !== false) {
            $prefix = $this->quoteTableName ( substr ( $name, 0, $pos ) ) . '.';
            $name = substr ( $name, $pos + 1 );
        } else
            $prefix = '';
        return $prefix . ($name === '*' ? $name : $this->quoteSimpleColumnName ( $name ));
    }
    
    /**
     * Quotes a simple column name for use in a query.
     * A simple column name does not contain prefix.
     * @param string $name column name
     * @return string the properly quoted column name
     * @since 1.1.6
     */
    public function quoteSimpleColumnName($name)
    {
        return '"' . $name . '"';
    }
    
    /**
     * Compares two table names.
     * The table names can be either quoted or unquoted. This method
     * will consider both cases.
     * @param string $name1 table name 1
     * @param string $name2 table name 2
     * @return boolean whether the two table names refer to the same table.
     */
    public function compareTableNames($name1, $name2)
    {
        $name1 = str_replace ( array ('"', '`', "'" ), '', $name1 );
        $name2 = str_replace ( array ('"', '`', "'" ), '', $name2 );
        if (($pos = strrpos ( $name1, '.' )) !== false)
            $name1 = substr ( $name1, $pos + 1 );
        if (($pos = strrpos ( $name2, '.' )) !== false)
            $name2 = substr ( $name2, $pos + 1 );
        if ($this->_connection->tablePrefix !== null) {
            if (strpos ( $name1, '{' ) !== false)
                $name1 = $this->_connection->tablePrefix . str_replace ( array ('{', '}' ), '', $name1 );
            if (strpos ( $name2, '{' ) !== false)
                $name2 = $this->_connection->tablePrefix . str_replace ( array ('{', '}' ), '', $name2 );
        }
        return $name1 === $name2;
    }
    
    /**
     * Resets the sequence value of a table's primary key.
     * The sequence will be reset such that the primary key of the next new row inserted
     * will have the specified value or 1.
     * @param CDbTableSchema $table the table schema whose primary key sequence will be reset
     * @param mixed $value the value for the primary key of the next new row inserted. If this is not set,
     * the next new row's primary key will have a value 1.
     * @since 1.1
     */
    public function resetSequence($table, $value = null)
    {
    }
    
    /**
     * Enables or disables integrity check.
     * @param boolean $check whether to turn on or off the integrity check.
     * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
     * @since 1.1
     */
    public function checkIntegrity($check = true, $schema = '')
    {
    }
    
    /**
     * Creates a command builder for the database.
     * This method may be overridden by child classes to create a DBMS-specific command builder.
     * @return CDbCommandBuilder command builder instance
     */
    protected function createCommandBuilder()
    {
        return new CDbCommandBuilder ( $this );
    }
    
    /**
     * Returns all table names in the database.
     * This method should be overridden by child classes in order to support this feature
     * because the default implementation simply throws an exception.
     * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
     * If not empty, the returned table names will be prefixed with the schema name.
     * @return array all table names in the database.
     * @since 1.0.2
     */
    protected function findTableNames($schema = '')
    {
        throw new CDbException ( Yii::t ( 'yii', '{class} does not support fetching all table names.', array ('{class}' => get_class ( $this ) ) ) );
    }
    
    /**
     * Converts an abstract column type into a physical column type.
     * The conversion is done using the type map specified in {@link columnTypes}.
     * These abstract column types are supported (using MySQL as example to explain the corresponding
     * physical types):
     * <ul>
     * <li>pk: an auto-incremental primary key type, will be converted into "int(11) NOT NULL AUTO_INCREMENT PRIMARY KEY"</li>
     * <li>string: string type, will be converted into "varchar(255)"</li>
     * <li>text: a long string type, will be converted into "text"</li>
     * <li>integer: integer type, will be converted into "int(11)"</li>
     * <li>boolean: boolean type, will be converted into "tinyint(1)"</li>
     * <li>float: float number type, will be converted into "float"</li>
     * <li>decimal: decimal number type, will be converted into "decimal"</li>
     * <li>datetime: datetime type, will be converted into "datetime"</li>
     * <li>timestamp: timestamp type, will be converted into "timestamp"</li>
     * <li>time: time type, will be converted into "time"</li>
     * <li>date: date type, will be converted into "date"</li>
     * <li>binary: binary data type, will be converted into "blob"</li>
     * </ul>
     *
     * If the abstract type contains two or more parts separated by spaces (e.g. "string NOT NULL"), then only
     * the first part will be converted, and the rest of the parts will be appended to the conversion result.
     * For example, 'string NOT NULL' is converted to 'varchar(255) NOT NULL'.
     * @param string $type abstract column type
     * @return string physical column type.
     * @since 1.1.6
     */
    public function getColumnType($type)
    {
        if (isset ( $this->columnTypes [$type] ))
            return $this->columnTypes [$type];
        else if (($pos = strpos ( $type, ' ' )) !== false) {
            $t = substr ( $type, 0, $pos );
            return (isset ( $this->columnTypes [$t] ) ? $this->columnTypes [$t] : $t) . substr ( $type, $pos );
        } else
            return $type;
    }
    
    /**
     * Builds a SQL statement for creating a new DB table.
     *
     * The columns in the new  table should be specified as name-definition pairs (e.g. 'name'=>'string'),
     * where name stands for a column name which will be properly quoted by the method, and definition
     * stands for the column type which can contain an abstract DB type.
     * The {@link getColumnType} method will be invoked to convert any abstract type into a physical one.
     *
     * If a column is specified with definition only (e.g. 'PRIMARY KEY (name, type)'), it will be directly
     * inserted into the generated SQL.
     *
     * @param string $table the name of the table to be created. The name will be properly quoted by the method.
     * @param array $columns the columns (name=>definition) in the new table.
     * @param string $options additional SQL fragment that will be appended to the generated SQL.
     * @return string the SQL statement for creating a new DB table.
     * @since 1.1.6
     */
    public function createTable($table, $columns, $options = null)
    {
        $cols = array ();
        foreach ( $columns as $name => $type ) {
            if (is_string ( $name ))
                $cols [] = "\t" . $this->quoteColumnName ( $name ) . ' ' . $this->getColumnType ( $type );
            else
                $cols [] = "\t" . $type;
        }
        $sql = "CREATE TABLE " . $this->quoteTableName ( $table ) . " (\n" . implode ( ",\n", $cols ) . "\n)";
        return $options === null ? $sql : $sql . ' ' . $options;
    }
    
    /**
     * Builds a SQL statement for renaming a DB table.
     * @param string $table the table to be renamed. The name will be properly quoted by the method.
     * @param string $newName the new table name. The name will be properly quoted by the method.
     * @return string the SQL statement for renaming a DB table.
     * @since 1.1.6
     */
    public function renameTable($table, $newName)
    {
        return 'RENAME TABLE ' . $this->quoteTableName ( $table ) . ' TO ' . $this->quoteTableName ( $newName );
    }
    
    /**
     * Builds a SQL statement for dropping a DB table.
     * @param string $table the table to be dropped. The name will be properly quoted by the method.
     * @return string the SQL statement for dropping a DB table.
     * @since 1.1.6
     */
    public function dropTable($table)
    {
        return "DROP TABLE " . $this->quoteTableName ( $table );
    }
    
    /**
     * Builds a SQL statement for truncating a DB table.
     * @param string $table the table to be truncated. The name will be properly quoted by the method.
     * @return string the SQL statement for truncating a DB table.
     * @since 1.1.6
     */
    public function truncateTable($table)
    {
        return "TRUNCATE TABLE " . $this->quoteTableName ( $table );
    }
    
    /**
     * Builds a SQL statement for adding a new DB column.
     * @param string $table the table that the new column will be added to. The table name will be properly quoted by the method.
     * @param string $column the name of the new column. The name will be properly quoted by the method.
     * @param string $type the column type. The {@link getColumnType} method will be invoked to convert abstract column type (if any)
     * into the physical one. Anything that is not recognized as abstract type will be kept in the generated SQL.
     * For example, 'string' will be turned into 'varchar(255)', while 'string not null' will become 'varchar(255) not null'.
     * @return string the SQL statement for adding a new column.
     * @since 1.1.6
     */
    public function addColumn($table, $column, $type)
    {
        $type = $this->getColumnType ( $type );
        $sql = 'ALTER TABLE ' . $this->quoteTableName ( $table ) . ' ADD ' . $this->quoteColumnName ( $column ) . ' ' . $this->getColumnType ( $type );
        return $sql;
    }
    
    /**
     * Builds a SQL statement for dropping a DB column.
     * @param string $table the table whose column is to be dropped. The name will be properly quoted by the method.
     * @param string $column the name of the column to be dropped. The name will be properly quoted by the method.
     * @return string the SQL statement for dropping a DB column.
     * @since 1.1.6
     */
    public function dropColumn($table, $column)
    {
        return "ALTER TABLE " . $this->quoteTableName ( $table ) . " DROP COLUMN " . $this->quoteColumnName ( $column );
    }
    
    /**
     * Builds a SQL statement for renaming a column.
     * @param string $table the table whose column is to be renamed. The name will be properly quoted by the method.
     * @param string $name the old name of the column. The name will be properly quoted by the method.
     * @param string $newName the new name of the column. The name will be properly quoted by the method.
     * @return string the SQL statement for renaming a DB column.
     * @since 1.1.6
     */
    public function renameColumn($table, $name, $newName)
    {
        return "ALTER TABLE " . $this->quoteTableName ( $table ) . " RENAME COLUMN " . $this->quoteColumnName ( $name ) . " TO " . $this->quoteColumnName ( $newName );
    }
    
    /**
     * Builds a SQL statement for changing the definition of a column.
     * @param string $table the table whose column is to be changed. The table name will be properly quoted by the method.
     * @param string $column the name of the column to be changed. The name will be properly quoted by the method.
     * @param string $type the new column type. The {@link getColumnType} method will be invoked to convert abstract column type (if any)
     * into the physical one. Anything that is not recognized as abstract type will be kept in the generated SQL.
     * For example, 'string' will be turned into 'varchar(255)', while 'string not null' will become 'varchar(255) not null'.
     * @return string the SQL statement for changing the definition of a column.
     * @since 1.1.6
     */
    public function alterColumn($table, $column, $type)
    {
        $type = $this->getColumnType ( $type );
        return 'ALTER TABLE ' . $this->quoteTableName ( $table ) . ' CHANGE ' . $this->quoteColumnName ( $column ) . ' ' . $this->quoteColumnName ( $column ) . ' ' . $this->getColumnType ( $type );
    }
    
    /**
     * Builds a SQL statement for adding a foreign key constraint to an existing table.
     * The method will properly quote the table and column names.
     * @param string $name the name of the foreign key constraint.
     * @param string $table the table that the foreign key constraint will be added to.
     * @param string $columns the name of the column to that the constraint will be added on. If there are multiple columns, separate them with commas.
     * @param string $refTable the table that the foreign key references to.
     * @param string $refColumns the name of the column that the foreign key references to. If there are multiple columns, separate them with commas.
     * @param string $delete the ON DELETE option. Most DBMS support these options: RESTRICT, CASCADE, NO ACTION, SET DEFAULT, SET NULL
     * @param string $update the ON UPDATE option. Most DBMS support these options: RESTRICT, CASCADE, NO ACTION, SET DEFAULT, SET NULL
     * @return string the SQL statement for adding a foreign key constraint to an existing table.
     * @since 1.1.6
     */
    public function addForeignKey($name, $table, $columns, $refTable, $refColumns, $delete = null, $update = null)
    {
        $columns = preg_split ( '/\s*,\s*/', $columns, - 1, PREG_SPLIT_NO_EMPTY );
        foreach ( $columns as $i => $col )
            $columns [$i] = $this->quoteColumnName ( $col );
        $refColumns = preg_split ( '/\s*,\s*/', $refColumns, - 1, PREG_SPLIT_NO_EMPTY );
        foreach ( $refColumns as $i => $col )
            $refColumns [$i] = $this->quoteColumnName ( $col );
        $sql = 'ALTER TABLE ' . $this->quoteTableName ( $table ) . ' ADD CONSTRAINT ' . $this->quoteColumnName ( $name ) . ' FOREIGN KEY (' . implode ( ', ', $columns ) . ')' . ' REFERENCES ' . $this->quoteTableName ( $refTable ) . ' (' . implode ( ', ', $refColumns ) . ')';
        if ($delete !== null)
            $sql .= ' ON DELETE ' . $delete;
        if ($update !== null)
            $sql .= ' ON UPDATE ' . $update;
        return $sql;
    }
    
    /**
     * Builds a SQL statement for dropping a foreign key constraint.
     * @param string $name the name of the foreign key constraint to be dropped. The name will be properly quoted by the method.
     * @param string $table the table whose foreign is to be dropped. The name will be properly quoted by the method.
     * @return string the SQL statement for dropping a foreign key constraint.
     * @since 1.1.6
     */
    public function dropForeignKey($name, $table)
    {
        return 'ALTER TABLE ' . $this->quoteTableName ( $table ) . ' DROP CONSTRAINT ' . $this->quoteColumnName ( $name );
    }
    
    /**
     * Builds a SQL statement for creating a new index.
     * @param string $name the name of the index. The name will be properly quoted by the method.
     * @param string $table the table that the new index will be created for. The table name will be properly quoted by the method.
     * @param string $column the column(s) that should be included in the index. If there are multiple columns, please separate them
     * by commas. The column names will be properly quoted by the method.
     * @param boolean $unique whether to add UNIQUE constraint on the created index.
     * @return string the SQL statement for creating a new index.
     * @since 1.1.6
     */
    public function createIndex($name, $table, $column, $unique = false)
    {
        $cols = array ();
        $columns = preg_split ( '/\s*,\s*/', $column, - 1, PREG_SPLIT_NO_EMPTY );
        foreach ( $columns as $col )
            $cols [] = $this->quoteColumnName ( $col );
        return ($unique ? 'CREATE UNIQUE INDEX ' : 'CREATE INDEX ') . $this->quoteTableName ( $name ) . ' ON ' . $this->quoteTableName ( $table ) . ' (' . implode ( ', ', $cols ) . ')';
    }
    
    /**
     * Builds a SQL statement for dropping an index.
     * @param string $name the name of the index to be dropped. The name will be properly quoted by the method.
     * @param string $table the table whose index is to be dropped. The name will be properly quoted by the method.
     * @return string the SQL statement for dropping an index.
     * @since 1.1.6
     */
    public function dropIndex($name, $table)
    {
        return 'DROP INDEX ' . $this->quoteTableName ( $name ) . ' ON ' . $this->quoteTableName ( $table );
    }
}
